To investigate etiology, detection, specific treatment modalities of malignant diseases in children. As a member of Children's Cancer Study Group A, a broad program in pediatric oncology which encompasses the Pacific Northwest. A regional center has been developed at this institution under the aegis of the above program. Children with acute lymphoblastic leukemia are placed on the group-wide protocol (which is being reported separately) with a current induction rate over the last three years of complete remission in 99% of the patients. According to present projected studies, it is anticipated that 50% of these children who undergo cranial spinal radiation continue maintenance therapy for three years will be in complete remission off the therapY at the end of five years. Similar programs in acute nonlymphoblastic leukemia presently give an induction rate of approximately 50% of the median survival of one year. In addition, studies are underway in the treatment of Wilm's Tumors according to the National Wilms' Study Project, neuroblastoma, osteogenic sarcoma with high dose Methotrexate and Citrovorum rescue, Ewing's sarcoma, rhabdkmyosarcoma, Hodgkin's Disease, lymphosarcoma and a newly inaugurated program in the chemotherapy of brain tumors. Approximately 100 new patients with malignant diseases are seen at this institution annually of which 40-50 patients have leukemia. A patient load of approximately 300 patients constitutes an ongoing study. Approximately 85% of all patients are placed on specific protocol study. In addition, a large supportive program in platelet transfusion, antibiotic therapy, and a psychosocial rehabilitation of children with malignant diseases is underway. A continuing improvement in the treatment of children with malignant diseases has been evident during the course of this project.